Technical mk1 punto hissing

[Nick540]

I'm new here but i have a problem with my mk1 sx85 16v punto it has a hissing sound from the rear of the engine and is making a deep note from exhaust and the exhaust and cat are brand new. it is also using more fuel than before and no leak.
any advice is good thanks nick

 

[s and b]

is it possible you have an engine problem as the hissing and fuel useage could be something like a burnt out exhaust valve
can you connect up a vacuum gauge on the inlet side and post up the results?

 

[Nick540]

don't think its broken valve as the level of hiss doesn't change when revved. i also shut have noted the when started cold it runs ruff and misfires and when i pull of my drive it cuts out and does till warm. a mechanic friend told me it might be the auto choke unit sticking

 

[Nick540]

hay I've uploaded a pic to my gallery take a look the torch is on the hissing area {https://www.fiatforum.com/gallery/data/500/medium/IMG_1949.jpg}

 

[s and b]

please dont ever pay your auto mechanic to do any work on your car because auto chokes went out with cortinas (ask your grandad)
its quite possible now i have more details that you have an air leak on the inlet side and this hiss is the inlet pulling in air
you need to get your snout in and find the hiss
of course it could also be a faulty one way valve on the brake master cylinder

 

[PuntoHowTo]

As a suggestion this could be an egr problem, the egr system makes quite a characteristic hiss if any of the pipes are damaged or broken, a tell tale sign would be exhaust smell under the bonnet